The arithmetic sequence $(a_i)$ is defined by the formula: $a_1 = -6$ $a_i = a_{i-1} + 3$ What is $a_{16}$, the sixteenth term in the sequence?
Answer: From the given formula, we can see that the first term of the sequence is $-6$ and the common difference is $3$ To find the sixteenth term, we can rewrite the given recurrence as an explicit formula. The general form for an arithmetic sequence is $a_i = a_1 + d(i - 1)$ . In this case, we have $a_i = -6 + 3(i - 1)$ To find $a_{16}$ , we can simply substitute $i = 16$ into the our formula. Therefore, the sixteenth term is equal to $a_{16} = -6 + 3 (16 - 1) = 39$.